CT 21 adheres to all solid, load-bearing and clean substrates free of substances which may impair adhesion. Aerated concrete blocks and sand-lime bricks must have a rough, open-pored surface.
Sprinkle CT 21 into clean, clear water and stir until completely free of lumps. Observe the following mixing ratio: 1 part by volume of water to approx. 2.5 parts by volume of mortar or approx. 7.4 l of water for 25 kg of CT 21. CT 21 is workable for about 4 hours. Apply the mortar with a notched trowel, blockwork trowel or notched spreader using the combing technique. Observe the open time of approx. 10 minutes. The position of the blocks can be adjusted for approx. 5 minutes after placing.